Gigas Larvae Day 4

My larvae are 60 microns now!

Today, Laura helped me screen my larvae through 60 micron and 48 micron screens. You can see the data for yourself here, but the majority of my larvae held on a 60 micron screen! Since there was really nothing in the 48 micron screens, I tossed out those samples. While I probably threw some slower-growing larvae down the drain, I also got rid of dead larvae that could possibly disrupt the healthier ones. Laura screened while I counted right away.

A few things I learned:

It’s much easier to count my larvae on a Sedgewick Rafter cell than in a well-plate

Yesterday, I was classifying larvae as dead if they didn’t show any signs of movement (both through the water column and their innards). This is incorrect! Larvae area dead when the shells are empty. I don’t remember seeing any larvae like that yesterday, but I think it’s safe to say that those data points are not high-quality. I shouldn’t use those counts in any analysis.

What I thought was a shell deformation was actually the larvae’s…butt?? It’s just a normal D-hinge larvae from a different angle! I realized this when I saw one of those weirdly-angled larvae do a few spings and flips, then start swimming in a way that was recognizable as a D-hinge

Notes from counting:

I knocked over the tripour with 48 micron Bucket 23 larvae before I could count it, so I don’t have that data

Tote 5 hit 34 ºC according to the immersion heater. I’m not sure how this happened. Laura mentioned that she set the temperature probe outside of the tote, which could have caused the tote to overheat. We removed the two buckets in there immediately (one was not stocked). Bucket 16 was sitting in the tote when the water was too hot. It was screened immediately after we removed it, and Laura said the water felt warm.

We turned off the heater and added colder seawater and waited for the temperature probe to read 25ºC

I also preserved larvae in the freezer and fed a mix of C.iso and Chagra since those were the most dense. It’s likely that I undercounted algal cells on the hemocytometer since there were so many! I was a little short on time so I also only counted three hemocytometer cells.

Another thing we noticecd when filling buckets is that the water in the heating reservoir had been sitting so long that the 1 micron filter was showing signs of being anoxic. We flushed the line and replenished the header a bit. Laura talked to Stuart, and they suggest draining the header tank tomorrow and flushing fresh seawater through that line so that it sits overnight. I would also have to make sure my water is heating overnight.